Exactly because their leveraged obligations and margin calls are in cash. And that is not Bitcoin "cash".
I don't think you're taking into account what demographic is actually being "squeezed" in a liquidity crunch. The people who own most of these things (BTC) are already rich in the first place and have no debt. The people who aren't rich and own them have some totally insignificant amount.
The real people getting squeezed are the middle class Americans with McMansions, private schools, and cars they can't afford. What is the common denominator of that group? They all own stocks and none of them own Bitcoin. People on the bottom and middle are the ones being squeezed. Stocks are mainstream, Bitcoin and gold aren't. Therefore, the stock dump will be horrific while things such as Bitcoin, as long as the confidence level is high (from 12.5 block reward halving bubble gains) will not only not go down, but will probably be going up as a safe haven from banks that will Cyprus you because Bitcoin is cash without counterparty risk.
Well I lately more and more realize that Bitcoin is funnel where n00bs come in to buy and miners cash out. The stalwarts don't buy more, as they are few in number and already have their big portion.
So an interruption in the stream of n00bs might have a domino deleveraging effect, since many people loan their BTC short to earn extra revenue.
Leverage may be hiding where you think you see only HODLers.
Also with the halving and marginal miners not wanting to turn their ASICs into door stops, they may be in a more strained position and need to deleverage in a contagion.
There is leverage from lending BTC for income, but if holders fear counterparty risk and instead pull their coins off exchanges that will only squeeze the shorts and drive the price higher, potentially much higher. I don't think anyone really knows how much short leverage is out there.
I'm ignoring halving effects, miner ASIC doorstops, etc. I don't know how to analyze that.